Jonny's making some nice headlines using Onyx. I've never really paid it much attention, but he's opened my eyes... Here's an opinion of mine. Lowercase white on black is sweet.
For those that are interested (from fonts.com):
"The Onyx font was cut by American Type Founders in 1937 and by Monotype in 1955. Onyx is one of the many variants on the nineteenth century fat face theme. A highly condensed and highly contrasted design where readability takes second place to style. This in no way detracts from its usefulness in carefully chosen applications, where it can create a feeling of refined and measured elegance. Use Onyx in large sizes where space is at a premium."